Controllable pitch marine propeller system



March 28, 1950 H. J. NNNNN LS v 2,501,908

/z J M04046,

March 28, 1950 H. J. NICHOLS 2,501,908 CONTROLLABLE PITCH MARINE PROPELLER SYSTEM Filed Sept. 29, 1945 4 Sheets-Sheet 2 1! J NICHOLS,

. March 28, 1950 H. J. NICHOLS CONTROLLABLE PITCH MARINE PROPELLER SYSTEM 4 Sheets-Sh et 3 Filed Sept. 29, 1945 March 28, 1950 H. J. NICHOLS CONTROLLABLE PITCH MARINE PROPELLER SYSTEM 4 Sheets-Sheet 4 Filed Sept. 29, 1943 glwuc w o fi NICHOLS Patented Mar. 28, 1950 CON TROLLABLE PITCH MARINE PROPELLER SYSTEM Harry J. Nichols, New York, N. Y. 1

Application September 29, 1943, Serial No. 504,333

20 Claims. 1

This invention relates to controllable pitch propeller system, and more especially to such a system adapted for use on motor boats, and has for its principal object the provision of a propeller system of the character described in which the pitch of the blades can be easily and accurately adjusted while the propeller is in motion under load and in which the blades will be automatically locked against displacement after such adjustment.

A further object is to provide an exceptionally simple, compact, and durable propeller hub and blade actuating mechanism which is economical to manufacture, easy to install and service, and provided with automatic controls, pitch block and pitch indicating devices and other practical features to facilitate operation by unskilled and nontechnical operators.

Another object is to provide a strong and rigid pitch varying mechanism which avoids any possibility of flutter or vibration of the blades in operation due to excessive elasticity or back-lash.

A further object is to provide a construction in which the gears of the primary actuating mechanism are relieved of any strain except when the pitch is being varied, thus reducing wear on the gear teeth and enabling relatively light gears to be employed. 1

A further object is to provide a pitch varying system of adequate angular range, including reversing and forward feathering of the blades, which is capable of changing the pitch in micrometric increments, yet also is capable of changing the pitch at a rapid rate for maneuvering and emergencies.

A further object is to provide a mechanical pitch limiting device toprevent the pitch being varied beyond the desired operating range, and a mechanical remotely indicating precision device to'indicate to the operator at all times, the relative angle of the blades.

With these and other objects in view, as well as other advantages incident to the improved construction, the invention consists in the various parts and combinations thereof set forth and 2 plated by the invention, drawings showing a preferred embodiment of the invention form part of this disclosure, and in such drawings like characters of reference denote corresponding parts in the several views in which- Fig. l is a side elevation in partial axial section of a marine variable pitch propeller and drive shaft therefor embodying certain features of the invention.

Fig. 2 is a transverse sectional view taken substantially on lines '2--2 of Fig. 1.

Fig. 3 is a detail view of the inner end of a blad root taken substantially on lines 3-4 of Fig. 2.

Fig. 4 is a side elevation in partial axial section of the gear mechanism and flange coupling forming part of the invention.

Figs. 5 and 6 are transverse sectional views taken substantially on lines 55 and 6-6, respectively, of Fig. 4.

Figs. 7 and 8 are axial sectional views in part and exterior end views, respectively, of the planetary differential device forming the transmitting end of the remote pitch indicator.

Fig. 9 is a schematic showing of typical pitch indicator instrument driven by the transmitter shown in Figs. 7 and 8. 1

Considering the invention as a whole, and referring particularly to Figs. 1, 2, and 4, a preferred construction of a variable pitch propeller system embodying the invention is shown as comprising a tubular main drive shaft lll having a collar or annular flange l I upset or otherwise provided thereon at its driving end, and driving a tubular propeller shaft I2, having a demountable flange 53, by means of a special flange coupling 4|] in which is housed a gear-driven screw-jack mechanism and other mechanism to be described in detail hereinafter. A propeller hub l5 having rotatable blades 46 is mounted on the outboard end of propeller shaft l2, the latter housing thrust rod I! which operatively connects the screw-jack mechanism in the coupling with the blade actuating mechanism within propeller hub 15.

The screw-jack mechanism, preferably rotatably driven by a pulley l8, flexible belt 20, and a reversible motor (not shown), is preferably mounted. inside the vessel at an accessible location, say at the'driving end of the engine. The entire pitch changing mechanism rotates bodily with the shafts at shaft speed, the gears and other parts of the mechanism being normally at rest relative to each other, while the motor turns idly. When the blade pitch is to he changed, the reversible motor is energized to rotate relatively in one direction or the other and drives the pulley l8 in one direction or the other relative to the shafts, thereby actuating transmission gearing and the screw-jack to produce a change of pitch as described hereafter in detail. The stationary planetary spur gear differential 2|, having two independent drive gears 22 and 23, is driven by suitable gearing on pulley l8 and flange l3 and in turn drives pitch indicating instrument 24 (see Fig. 9) by a flexible shaft 25, or other suitable means, to provide remote precise indication of the pitch angle.

The controls for the reversible motor are not part of the present invention, andare described:

in detail in my copending application Serial No; 433,991, filed March 9, 1942, now U. 2,363,191.

Referring now to the drawings in detail and particularly to Fig. l, the propeller of ie invention is shown as comprising a sectionalhub l comprising a forward portion 28 which is fixed to thetubular propeller shaft i2 by a. tapered; splined connectionand nut 21', as shown;

on by other suitable construction; and an after portion 31: which. is secured: to the forward. portion 28 by longitudinally extending boltsfi. Zhis structure mounts the blades and: houses the blade actuating mechanism.

The" two portionsofi the hub are provided with a plurality of radially extending bores formed with inner and outer seats and an intermediate annular shoulder 39. Blades- 16, each: having a root! portion spindle (H, are journalled for axial rotation in the radial bores for the purpose. of angular pitch: adjustment, eacli' blade having an annular toothed ring 32 mounted: on. and secured: to its inner end by means of screws 33. A pack ing: gasket 34 of any preferred type .isassembled between theblade root 3i and shoulder 36 to prevent leakage of lubricant and entrance of water intorthe hub.

The blades it can. be rotated in the hub to vary: their pitch from the full? forward (feath pressing theknurled endi 38 of the stud. into aliole bored; axially in the hubportion 3?. This construction enables the wedge to be reciprocated by the thrust rod ll, but neither the Wedge nor-the thrust'rod can turn relative to the hub. The rings 32, each attached to a blade root' or spindle, areeach provided with a toothed annu- Tar segment projecting from the face of'the ring and adapted to engage jointly the teeth ol'wedgc 35". (See Fig. 2.)

crowngear.

Referring toFig. 3 the toothed-segment of ring 32- is' provided with skewed teeth 39 similar to those" of a' skew crown gear, these'teeth being preferably formed by a" reciprocating generating cutter havinghelical teeth similar in form tothose of'the cylinder wedge 35. Asis well understood, the shape of the sector teeth will be conjugate to that of the wedge teeth at'each point of contact.

The. cavity of'hub I5 is provided with a supply of, lubricant, which provides lubrication for the workingparts of the hub mechanism.

It will be evident that with the construction S. Patent. No.

Each ring thus constitutes a shown, the blades l6 will be rotated in unison as the wedge 35 is reciprocated by thrust rod 17.

Referring now to Fig. 4, which shows the details of the driving mechanism for reciprocating thrust rod l'l, this mechanism comprises a unitary assembly 40 including the coupling connecting propeller shaft 12 to drive shaft Ill, as for example the drive shaft of a prime mover. The drive: shaft- HE' is. shown 8.5a being.-; provided with a conventional upset flange H, while the propeller shaft I2 is preferably provided with a demountable flange l3, fixed on the propeller shaft by a tapered). splined connection and nut M, thereby to enable the propeller shaft to be withdrawn rcarwardly through the propeller shaft bearings (not shown) when flange i3 is dismounted. Thev flanges H and I3 are strongly clamped to the couplingring by plural bolts 43 and l i-inzwell known manner.

The inner end of thrust rod l 'l' is provided with strong threads-451. and: is mountedso as to be slidable' coaxially.- in: the bore of; shafts: it and 5.2.- A rotary nutt iEi-is journalled freelyon threaded.- PGIt-iOITAE-iOf: thrust rod ll between-flange l l and the ends of the thrust. rod, nut 4e being the hub of arrexternali spur gear 41L This: gear driven forthes. purpose of varying the" blade pitch bytransmission gearing comprising: a: plurality of stationary pinions 5E journalled recesses in: the coupling ring 50 and flange II, and meshing. with; an. internal ring gear El cutin. the inner perimeter-of floating. pulley: 18., which is rotatabiy: mounted between. flange H and ring 53. (See Fig; 4';

Byrreferring'tdi igz 5, it is-seen. that. whenbelt Zit drives pullcy 18: in: one direction or the other relative! to ring 5%, ring, gear 5ldrives pinions- 52 in the same direction and; external gear ll irrthe oppositerdirection, thereby turning nut hi I onscrew Hi For: the purposes-cf? limiting thezpitch change tea-predetermined operating range, a pitch block mechanism: ispro-vided, although of course this feature: can. be omitted. without detriment. to the other features;oi;the-invention. Referring again. toiFig; 4', the? Webof: gear 3 1- mounts;a. fixed stud 53; on which: is j'ournalleds a planetary pinion 54- which meshes in common with a stationary, internal' gear 5'52 cut. intheinternal bore of ring 50, and with afioating internal ring. gear rotat-- abl mounted inside: ring 50.. Gears 55 and 55 are preferably cut to the same. pitch circle, but

difien' slightly as to the numebr of teeth, say by one=tooth'. A portion ofring gear 58 works in an annular groove 5'! cut in the face. of flange $3.. and the outer perimeter of that gearis provided with a cam rise or traveling. stop. member 5.8 which forms; par-tot: the pitchblock-device (see Fig. 6). Twohardened'steel rollersiiil-are journalled: loosely in ring. Slat suitable positions to be intercepted by stop member-5%when the latterh'as travelled the predetermined angular him it's made permissible by the limitations of the blade actuating mechanism. One of the stop. rollers 60 1s preferably set to the limitwhere the blades would be" fullyfeathered forward, WIlflGi't'hG other roller would preferably be set at the desired maximum reverse blade position, say at a pitch. of 30;

Referring'toFig; 6; the operation of the pitch blook'device is as follows: When pulley l8 drives the pitch changing-gearing, planetary pinion 54 whichis carried by gearv 41' rolls around in in:-' ternal" gears 55and 56 and due to the differential number of teeth in these gears, ring gear 56 is caused to creep gradually relatively to, gear 55, hence cam rise 58 moves away from the midposition shown in Figure 6. In the event the pitch change is carried to either limit, the cam rise '58 encounters one of the rollers 6!]- which, as it ascends the cam rise, jams between the outer rim of gear 56 and the inner surface of drum 6|, thereby stopping rotation of drum 6| which is integral with pulley I8. The action is similar to that of well-known roller clutches and overdrive devices, and checks the relative motion of pulley I8 in a positive manner without undue shock. The torque of the pitch drive motor is overcome by the braking action on pulley I8 until such time as the rotation of the'motor is reversed, whereupon the motor is able to unlock the clutch and set the gearing in rotation in the opposite direction towards the alternate pitch stop. It will be apparent to those skilled in the art that the construction described provides an exceptionally simple, effective and practical pitch block device.

Referring now to Figs. 4, '7, 8, and 9, for the purposes of providing remote precise indication of the pitch angle by mechanical means, addi tional mechanism is provided as follows: Flange I3 is provided with an external spur gear 62, while the drum portion SI of pulley I8 is provided with an equal external spur gear 63, these gears meshing respectively with equal gears 22 and 23, which drive planetary differential gear unit 2|. Referring particularly to Figs. 7 and 8, the differential gear unit comprises a split casing 2I, comprising two portions bolted together as shown, housing planetary spur gear mechanism driving a shaft 64 which turns proportionally to the difference in angular relation between gears 22 and 23, which latter are mounted fixed on independent coaxial drive shafts 65 and 66, respectively. Hollow shaft 65 is provided with a flange 61 having a stud 68 on which is journalled first planetary pinion PI meshing with stationary internal gear GI and floating internal ring gear G2 mounted in a ball bearing ID, these latter gears being out to the same pitch circle, but differing slightly, say by one tooth. Shaft 66 is provided with a flange 'II carrying a stud similar to stud 68 on which is journalled second planetary pinion P2 meshing with gear G2 and driven internal gear G3, the latter gear having the same number of teeth as the stationary gear GI. Gear G3 is preferably integral with driven shaft 64. The casing 2i and shaft 64 are adapted'for connection to a flexible drive shaft 25 and flexible casing I2 therefor in well known manner.

The operation of the planetary differential spur gearing is as follows: Assuming first that gears 22 and 23 are being driven at the same speed. the first and second planetary pinions PI and P2 roll around in unison in the internal gears GI, G2, G3. For each planetary revolution of these pinions, due to the difference in the number of teeth, gear G2 gains (or loses) one tooth pitch over gear GI, while gear G3 loses (or gains) one tooth pitch over gear G2. The net result is that gear G3 rotates at the same rate as gear GI, that is, it remains stationary. Now assume that gear 22 rotates faster than'gear 23, so that pinion PI revolves faster than pinion P2, then when PI gains one planetary turn relative to P2, gear G3 will have gained one tooth pitch relative to gear GI. This is apparent if it is considered that gear 22 is rotated one turn while gear 23 is held stationary, whereupon pinion PI meshes with all the teeth of gear GI and with the same number of. teeth of gear G2 that is, with one more (or less) of the teeth of gear G2, whereby gear G3, which is coupled to gear G3 by pinion P2, gains (or loses) one tooth pitch relative to gear GI. It is readily seen that if gear 22 is held while gear 23 is rotated one turn the result will be equal but opposite to that obtained in the previously assumed case. It is to be noted that in order to obtain the result just described, the product GI/ G2 G2/ G3 must equal one, where the gear designations represent the number of teeth in those gears.

The gear system described operates according to the operational equation:

n=revolutions of driven gear G3 a1=revolutions of first planetary carrier 61 az=revolutions of second planetary carrier II ei firs-t train factor=GI/G2 e2=second train factor=G2l G3 Therefore, it follows that shaft 64 rotates proportionally to the angular difference between gears 22 and 23, which turn proportionally to the angular difference between gears 62 and 63, which latter difference in turn represents proportionately the pitch angle of the blades relative to the shaft. Thus the rotation of shaft 64 reflects proportionally the pitch angle of the propeller blades and the pitch measuring mechanism described constitutes a form of angle micrometer.

It is further to be noted that the planetary spur gear differential device described provides a relatively great speed reduction between the rates of relative rotation of the input shafts 65, B6, and the rotation of output shaft 64. For example, assume that gears GI and G3 have 99 teeth, while gear G2 has teeth. Then the speed ratio between shaft 65 and gear G2, and between shaft 66 and gear G2 will be 100:1; or otherwise stated, the input shafts will require a relative rotation of 100 turns for each turn of the output shaft. By comparison, the conventional bevel gear differential gearing disclosed by the prior art provides a speed reduction of 2:1 between the differential shafts. This large speed reduction ratio is a highly advantageous feature of the differential device of the invention. since it is evident that in order to provide the strong torque requisite to rotate the blades while under load, the pulley I8, which carries gear 63, must rotate a hundred or more turns relative to the shaft for each axial turn of the blade. Further, this large speed reduction ratio eliminates the need of the high ratio, speed reducing gear-trains preceding or following the differential shafts of the prior art, and yet enables the remote angle indicating instrument and its connecting link to operate at a low, and favorable speed. An over all advantage in the apparatus and operation of pitch indicators is thus secured.

Referring now to Fig. 9, flexible shaft 25 operatively connects the differential unit 2| with the visual pitch indicatinginstrument 24. The construction of suitable angle indicating instruments being well known, and various types being suitable for the purposes of the present invention,

detailed description'is considered unnecessary.

As a typical example, the flexible shaft 25 drives ZJELMQBZ moving along an arcuate scale 1.4, suitably graduated to: show the as-tern (or reverse). ahead, and featheredranges as shown. The pointer' in.- di'cates the pitch angle of. theblades. directly in degrees, so: that th'e operator'- is constantly apprised? of the: pitch. conditions. The pitch block device previously described prevents theblade pitch fronrexceeding the desired operating range, hence there is no danger of the pitch varying. mechanism being. deranged or damaged. by careless or improper operation.

The motor control: apparatus described" in my; copending application. Serial No. 433,991,. filed March 9, 194-2, now abandoned; enablestthepitchof the blades to be. varied. at will, or automatically by suitable control of instruments...

Without further description, it is believed evident that the mechanism of the invention provides a" powerful; practical and efficient means for varying the blade pitch under all operating conditions. It is also to be noted particularly that the construction of variable pitch propellers provided by the invention is readily adaptable to equipping existing vessels. with such propellers without extensive alteration of conventional propulsion" arrangements.

I claim:

1. In a mechanical operating device for a variable pitch propeller blade mounted on a hollow'hub-on a hollow'shaft', a hollow drive shaft, a mechanical coupling-for'said drive shaft, means mounted in saidhub and shafts for varying the pitch of said blade while in rotation, including a reciprocating screw member slidable coaxially iii'said shafts, means mounted in said couplingfor translating said screw member including a rotary free nut mounted on said screw member, powertransmiss-ion gear means for rotating said nut, and external drive means for said gear member including a ring drive member rotatable con centrically on said coupling, a first drive means carried by said ring member, a second drive means carried by said coupling, and stationary differential means. jointly driven by said first. and second. drive means for mechanically indieating the pitch of'the aforesaid propeller blade.

In a mechanical operating device for a. variable pitch propeller blade mounted on a hollow hub on a hollow propeller shaftv driven bya mechanical. coupling, means. mounted. in. said. hub, shaft, and. coupling for. varying the pitch of. said blade-While inirotation, including blade. turningv mechanism in said. hub, a reciprocating member slidable coa-Xially in said. shaft and 6X? tending from said coupling to said hub for actuatingsaid turning. mechanism,- translating. meansassembled insaid coupling for reciprocatingsaidmember including:v a ring, drive member for. said translating meansrotatable: concentrically on said coupling, a first drive member carriedby said ring membena second drivemember carried. by said. coupling, and stationary means jointly dr-ivenby said-first and-second drive memhers-for mechanically indicating the pitch of the aforesaid propeller blade.

3. In remotely indicating. pitch indicator meanszior variable pitch". propellers, a-difierential. planetary gear. mechanism. inoludingxtwo inde:-- pendent drive shafts. each adapted. to drive a rotary member carrying a planetary pinion, astationary internal gear meshing with one of said piniona, an intermediate rotatable internal gear. meshing'with bothpinions, and a driven internal gean'meshing, with the other pinion, whereby the" rotation. of the driven gear. is. proportional tot-the angular: relation of the two drive shafts.

4 The mechanism of claim: 3, in which the production the. number of teeth in the first pin.- ion. times those. in. the driven gear divided by. the productof; the'number of: teeth in thesecond.

pinionntimes-thosein the stationary gear equals 1 one.

5;. In: remotely. indicating pitch angle indicators, the combination comprising an instrument. for indicating anglesvisually, a driving connection. therefor, and: a unitary planetary spur gear differential mechanism of large speed reduction ratiofonactnating: said driving connection. com.- prising. two independent coaxial drive membersadapted. tobe driven in the same direction and each carryinga: planetary pinion mes-hing with an: individualinternal. gear and meshing in commen with a floating: internal gear having a slight ly different number of teeth than said individual gears, onezofthe-individual gears being station-- ary, While the other individual gear constitutes" the driven gear of the gear mechanism and is caused to rotate'by said drivemembers in diminished proportion tothe differential angle: of said.

drive members.

6. In mechanical operating. mechanism for a variable pitch propeller blade-mounted-on a tubularshaft, the combination with blade actuating mechanism carried by said shaft for varying the blade pitch including a rotary drivemember for drivin'g'said' actuating mechanism, of a coupling for' driving: said shaft,. and mechanical means. housed in said coupling for limiting the pitch: of said blade to a predetermined range of operation comprising traveling stop means adapted to be: driven: by said rotary drive member, gear mechanism operatively connected with said drive member for rotating said stop means in diminished proportion to the relative rotation of saiddrive member, and releasable locking means" adapted to coast with said stop meansand saiddrive member for preventing further rotation of. said drivemember in the same direction relative to the coupling at predetermined" angular limits.

7'. Int mechanical operating mechanism for a: variable pitchpropeller blade mounted'on a tubu lar shaft; iii-combination with a mechanical coirplingfor driving-said shaft. of mechanism carried 2 by said. coupling for-limiting the blade pitch to' predetermined limits comprising a rotary'drivemember'mounted concentrically on said coupling, rotary means operatively connected with said" drive member and adapted to rotate in diminished proportion thereto, and'clutch means actuated by said rotary means for stopping rotation of said rotary drive'member" relative to said cou--- pling when the predetermined pitch limits are approached.

8. In a differential speed reducing device for" angle indicators, a planetary differential spur gear train having a train factor of plus one and comprising, a stationary internal gear, an inter-: mediate gear having one tooth more" or less than said? stationary gear rotatably mounted coaxially with said internal gear, a driven internal gear' equal to said. stationarygear and rotatably mounted coaxially therewith, a pair of planetary pinions eaoh meshing' with one of said equalgears and'in common with the intermediate gear, and two independently rotatable driving carriers for said planetarypinions.

9; A mechanical. differential movement com-,2 prising two independent input" drive shafts,;av driven output shaft, a: stationary internal. gean mounted in concentric relation to at least one of said shafts, a rotary member carrying a planetary pinion having a driving connection to one of said input shafts and meshing with said stationary gear, an intermediate rotatable internal gear meshing with both pinions, and a driven internal gear meshing with the second planetary pinion and having a driving connection with said output shaft, whereby the rotation of the output shaft is proportional to the differential rotations of said input shafts when said shafts are in relative rotation.

10. A differential planetary spur gear mechanism comprising two independent rotary drive members each operatively connected with a rotary member carrying a planetary pinion, a stationary internal gear meshing with one of said pinions, an intermediate rotatable internal gear meshing withboth pinions, and a driven internal gear meshing with the other pinion, whereby the rotation of said driven gear is proportional to the differential rotations of said drive members when in relative rotation.

11. A mechanical differential movement characterized by a large speed reduction ratio comprising two independently rotatable driving members, a stationary spur gear mounted in coaxial relation to one of said members, an equal driven spur gear rotatably mounted in coaxial relation to said stationary gear, an intermediate rotatable spur gear having a slightly different number of teeth than the aforesaid internal gears and mounted in coaxial relation thereto, a planetary pinion rotatably mounted on one of said driving members and meshing with said stationary gear and said intermediate gear, and a second planetary pinion rotatably mounted on the other of said driving members and meshing with said intermediate gear and said driven gear.

12. A planetary differential all spur gear mechl anism having two epicyclic gear trains in differential combination comprising two independent driving planetary carriers, a stationary spur gear, a driven spur gear, an intermediate spur gear, and double planetary pinions carried individually by said planetary carriers and meshing in common with said intermediate gear and individually with said stationary and said driven gears respectively, wherein the epicyclic gear trains in combination operate according to the equation:

13. In combination with pitch changing mechanism for a variable pitch propeller having means carried by the propeller shaft for adjusting the pitch of the propeller blades while said shaft is in rotation under load, including a driven rotary member mounted concentrically rotatable with respect to said shaft in angular coordination with the pitch angle of said blades; a rotary member concentrically fixed to said shaft, pitch measuring mechanism adapted to be driven jointly by said rotary members including a stationary unitary spur-gear differential angle reducing device, means operatively connecting said rotary members individually to said device, and a pitch angle indicating instrument connected to be driven by said device so as to indicate the pitch angle of the propeller blades.

.14. A variable pitch marine propeller system including a hollow propeller shaft, a hollow hub fast coaxially thereon, a mechanical drive coupling therefor, and having, in combination, a plurality of blades each with a spindle journaled radially in said hub, mechanism mounted in said hub, shaft and coupling for varying the pitch of said blades including a blade turning movement mounted within said hub comprising a reciprocable cylinder wedge and a driven crown gear fast on each said spindle in mesh with said cylinder wedge, a reciprocable rod movable coaxially in said shaft and extending from said coupling to said hub and fast to said cylinder wedge, and mechanism mounted in said couplingfor reciproeating said rod with respect to said shaft including a screw-jack mechanism and torque transmission gearing for actuating said screw-jack mechanism including a reversibly driven ringgear drive member for said gearing mounted concentrically and rotatably on said coupling.

15. A controllable pitchmarine propeller including a tubular propeller shaft having, in combination, a streamlined hollow hub fixed tightly on said propeller shaft and having an axial bore, a plurality of axially rotatable blades each having a spindle journaled radially in said hub, a cylinder wedge and crown gear movement for rotating said blades axially in unison for the pur pose of varying their pitch comprising an indie vidual segmental crown gear fixed rigidly to each of said spindles and having multiple skew teeth, a wedge member mounted in said bore for axial translation having the form of a right circular cylinder with external helical gear teeth adapted to mesh in common with successive teeth of said crown gears; and a reciprocable rod mounted coaxially within said shaft and extending intosaid hub connected so as to impart translatory movement to said wedge member, thereby to cause said wedge member to impart rotary movement to said crown gears by wedge action.

16. A controllable pitch marine propeller having, in combination, a streamlined hollow hub having an axial bore and angularly displaceable blades each having a spindle journaled radially in said hub, a wedge and gear movement mounted within said hub for displacing said blades in unison comprising an individual crown gear having multiple skew teeth fast to the spindle of each blade, a wedge member mounted in said bore for reciprocation therein and having the form of a cylinder of revolution provided with external helical gear teeth adapted to mesh successively with said skew teeth of said individual gears, and 'means for reciprocating said wedge member, thereby to impart a rotary movement to said crown gears by wedge action of said helical teeth on said skew teeth.

1'7. In a controllable pitch marine propeller including a streamlined hollow hub having an axial bore and blades with spindles journaled radially in said hub, a wedge and gear movement mounted entirely within said hub for varying the pitch of said blades comprising a segmental crown gear fast rigidly on each said spindle and having multiple skewed teeth, a coacting toothed wedge member axially reciprocable in said bore, and having the external form of a helical pinion, and guide means fixed in said hub and adapted to guide the movement of said wedge member.

18. A controllable pitch marine propeller system including a tubular propeller shaft, a drive shaft therefor, a hollow coupling assembly for said shafts, and a hollow hub mounting a plurality of radial, axially rotatable blades fast 00-- axially to said propeller shaft; in combination: a mechanical movement mounted in said hub for rotating said blades axially comprising a partial crown gear fixed on the root portion of each blade, and an axially translatable cylinder wedge ancient liavingextemal"helical gear teeth meshing zopera tively with .said crown gears mou'nted I'coaxially in said hub; and :pitch changing mechanism mounted in said shafts and coupling ieompnising 2a reciprocable oomiecting mod extending eoaxiauy through said propeller shaft to translate :said wedge, pow'er screw-jack mechanism :mounted in said coupling for reciprocating said connecting rod including a irotary but non-tifanslatable nut mounted iiin said coupling :on a threaded =portion of said rod, torque ti an smissionngearing' :mounted in-isai'd coupling for rotating asaidilnut while fs'aid shafts are in rotation including :a :ringegear driving member for said -gearing mounted concentnically and mot-atably on said vcoupling; and power transmission means external to said coupling :ior driving said ring-gear .-'r'eversibly.

l9. SIn a controllable pitch imarine propeller including a i-h'ollow hub having :an axial ibore mounting aEIillll'HlitY of axiallyrrotatalil'e :blades each having a spindle journaled radially linrsaid hub; in. mechanical movement Within 'said hub for :rotating said fblades raxially in unison for purposes of varying their :pitch comprising a seemental crown gear, having :skew teeth *on the face thereof ,fix'edsrigidly ion thezinnerfend of each spindle, .and 'a .:recip1-:ocable wedge \member having the general form of :a cylinder of revolution with helical :gear teeth nut in :its :periphery and adapted :to mesh isuccessively with said skew l teeth.

L20. 'HZhe combination "with e tcontrollable vpitch propeller including an axially i-rotatable bla'de mounted on a propeller shaft; of *means v for tso rotating :sa'id blade including a rotary driven member rotatable concentrically withirespe'ct to said ishaft and icoordinaition with :the rotation ofwrsaid blade; a rotary member fast concentri cally 'on rsaiid 'shaft; a stationary unitary difierthereby to emdicate atheizpitchof said'propeller.

J. NICHOLS.

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